An expression of confusion, used when mis-hearing or misunderstanding what some one has said. Especially applicable in the situation where a girl says something that you THINK was kinda sexual but it's so unexpeceted you're not entirely sure.

Comes from the cancelled TV show Firefly (the episode "Our Mrs Reynolds") - taken from the point where the naked girl asks the captain if they're married "are they not to become one flesh?" To which he replies: "to-wubba-who?"

Boy: (packing a rucksack) "I don't think I can fit all of this in here..."
Girl: "Ha! That's what she said..."
Boy: "To-wubba-who?"
Girl: (sniggers)
Boy: "...did you just say 'that's what she said'?"